﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Drawing;
using System.Web;
using System.IO;
using System.Drawing.Imaging;

namespace Aij1.Utils
{
    public class CheckCodeCreater
    {
        static Color[] color = { Color.Black, Color.Red, Color.Blue, Color.DarkGreen, Color.DarkBlue };
        //字体列表，用于验证码 
        static string[] font = { "Times New Roman", "MS Mincho", "Book Antiqua", "Gungsuh", "PMingLiU", "Impact" };
        //验证码的字符集，去掉了一些容易混淆的字符 
        static char[] character = { '2', '3', '4', '5', '6', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'R', 'S', 'T', 'W', 'X', 'Y' };

        string CheckCodeString;

        HttpResponse Response { get { return HttpContext.Current.Response; } }

        Bitmap CheckCodeImage;

        static string defaultName = "sdpoa@d*o!i#fpaf";

        public CheckCodeCreater(string key)
        {
            if (String.IsNullOrEmpty(key)) key = defaultName;
            CheckCodeString = string.Empty;
            //颜色列表，用于验证码、噪线、噪点 
            Random rnd = new Random();
            //生成验证码字符串 
            for (int i = 0; i < 4; i++)
            {
                CheckCodeString += character[rnd.Next(character.Length)];
            }

            HttpContext.Current.Session[key] = CheckCodeString;

            CheckCodeImage = new Bitmap(100, 40);
            Graphics g = Graphics.FromImage(CheckCodeImage);
            g.Clear(Color.White);
            //画噪线 
            for (int i = 0; i < 10 / 2; i++)
            {
                int x1 = rnd.Next(100);
                int y1 = rnd.Next(40);
                int x2 = rnd.Next(100);
                int y2 = rnd.Next(40);
                Color clr = color[rnd.Next(color.Length)];
                g.DrawLine(new Pen(clr), x1, y1, x2, y2);
            }
            //画验证码字符串 
            for (int i = 0; i < CheckCodeString.Length; i++)
            {
                string fnt = font[rnd.Next(font.Length)];
                Font ft = new Font(fnt, 18);
                Color clr = color[rnd.Next(color.Length)];
                g.DrawString(CheckCodeString[i].ToString(), ft, new SolidBrush(clr), (float)i * 20 + 8, (float)8);
            }
            //画噪点 
            for (int i = 0; i < 100 / 2; i++)
            {
                int x = rnd.Next(CheckCodeImage.Width);
                int y = rnd.Next(CheckCodeImage.Height);
                Color clr = color[rnd.Next(color.Length)];
                CheckCodeImage.SetPixel(x, y, clr);
            }
            g.Dispose();
        }

        public void Write()
        {
            //清除该页输出缓存，设置该页无缓存 
            Response.Buffer = true;
            Response.ExpiresAbsolute = System.DateTime.Now.AddMilliseconds(0);
            Response.Expires = 0;
            Response.CacheControl = "no-cache";
            Response.AppendHeader("Pragma", "No-Cache");
            //将验证码图片写入内存流，并将其以 "image/Png" 格式输出 
            MemoryStream ms = new MemoryStream();
            try
            {
                CheckCodeImage.Save(ms, ImageFormat.Png);
                Response.ClearContent();
                Response.ContentType = "image/Png";
                Response.BinaryWrite(ms.ToArray());
            }
            finally
            {
                //显式释放资源 
                CheckCodeImage.Dispose();
            }
        }

        public static bool IsValid(string key, string value)
        {
            if (String.IsNullOrEmpty(key)) key = defaultName;
            bool valid = CommOp.ToFullStr(HttpContext.Current.Session[key]).Equals(value, StringComparison.OrdinalIgnoreCase);
            return valid;
        }

        public static void Clear(string key)
        {
            HttpContext.Current.Session[key] = "验证码已过期&!#LIPLz;las";
        }
    }
}
